Rolling diaphragm seal means for removing and recovering diffused gas



Jan. 6, 1970 R. J. MEUER ETAL ROLLING DIAPHRAGM SEAL MEANS FOR REMOVINGAND RECOVERING DIFFUSED GAS Original Filed Dec. 16, 1965 3 Sheets-Sheet1 Jan, 6, 197@ m, J, MEUER ETAL. 3,48%?11 ROLLING DIAPHRAGM SEAL MEANSFOR REMOVING AND RECOVERING DIFFUSED GAS Original Filed Dec. 16, 1965 3Sheets-$heet 2 Jan. 1979 R J MEIJER ETAL ROLLING DIAPHRAGM SEAL MEANSFOR REMOVING AND RECOVERING DIFFUSED GAS 1965 3 Sheets-Sheet 3 OriginalFiled Dec. 16,

I J mglswrow United States Patent ABSTRACT OF THE DHSCLGSURE A partitionwall permitting difiusion for removing and recovering gas ditfusedthrough a rolling diaphragm seal into a liquid diaphragm supportingcolumn. The device includes a means for maintaining a pressuredifferential across the diaphragm seal and a liquid storage chamber. Thedevice also makes use of wire gauzes as a separator in a liquidcontainer.

This application is a continuation of application Ser. No. 514,293 filedDec. 16, 1965 and now abandoned.

The invention relates to a device constituting a seal constructed as arolling diaphragm between two coaxially arranged elements which aremovable relative to one another, the said seal separating two spaces,one of the said spaces being filled with a liquid and the other spacebeing filled with a gas.

Examples of known devices of the type to which the present inventionrelates are hot-gas reciprocating engines, compressors and expansionmachines. In these machines the rolling diaphragm is provided as a sealbetween the piston and the cylinder and forms with its one side part ofthe boundary of the working space. With its other side the rollingdiaphragm engages liquid which serves as a support for the rollingdiaphragm. It is desirable in these cases that the said liquid is atleast substantially incompressible.

It has been found that during operation a certain diffusion of gasoccurs out of the working space through the rolling diaphragm into theliquid. This diffusion greatly increases as the temperature rises. Aftersome time if no preventative measures are taken, the concentration ofthe gas dissolved in the liquid exceeds the saturation concentration.This results in bubble formation meaning that the liquid no longer isincompressible. As a consequence even at a constant differentialpressure across the rolling; diaphragm the said rolling diaphragm willnevertheless vary in length. This, of course, adversely influences thelife of the rolling diaphragm.

To prevent the occurrence of bubble formation in the liquid it is knownto regularly refresh the liquid in the space under the rollingdiaphragm. In this case a certain stream of liquid which contains littleor no dissolved gas is continuously supplied to the space whilesimultaneously the same stream of liquid but now with a higherconcentration of dissolved gas, is directed away from said space. Inthis manner the concentration of dissolved gas can be kept below thesaturation concentration. However, a disadvantage of the said method isthat the gas diffused through the rolling diaphragm is lost. The costmay be considerable particularly in case of more expensive types of gas.

A principle object of the invention is to provide a solution to theabove described problem in which the concentration of dissolved gas inthe liquid space remains 3,487,751 Patented Jan. 6, 1970 below thesaturation concentration and the gas diffused by the rolling diaphragmis not lost.

The device according to the invention is characterized in that itincludes a separator to remove and receive gas diffused through therolling diaphragm out of the liquid.

The gas separated out of the liquid can subsequently be supplied againto the working space.

One embodiment of the device according to the invention comprises aseparator that is formed by at least part of the wall of the space whichcontains the liquid, which part of the wall is manufactured from amaterial which permits diffusion of the gas concerned, the said part ofthe wall making a boundary with its side remote from the liquid space astorage container in which a pressure prevails which is lower than thepressure in the liquid space.

The gas diffused from the working space through the rolling diaphragmwill then leave the liquid space through the said part of the wall. Inthis manner the end in view, namely recovery of diffused medium, isachieved with an extremely simple construction. Under certaincircumstances the part of the wall which permits diffusion may beconstituted by a second rolling diaphragm which faces the liquid spacewith its concave side.

A further embodiment of the device: according to the invention, in whichat least one liquid supply duct and at least one liquid exhaust ductcommunicate with the liquid space, comprises a separator which isconstituted by a container consisting of at least two parts, the partsbeing separated from one another by a wall permitting diffusion of thegas concerned, the liquid exhaust duct communicating with the first partof the container which is provided with a further duct whichcommunicates, if required, through a control mechanism with the supplyduct to the liquid space. A pumping device is further provided fortransporting liquid out of the first part of the container back to theliquid space and a pressure prevails in the second part of the containerwhich is lower than the pressure in the first part of the container.

In said further embodiment liquid is always circulated by pumping, inwhich the pump need overcome only the resistance to flow of the ducts inquestion. When the liquid space is constructed so that the volume ofthat space remains constant when the elements move relative to oneanother and no leakage occurs, no further control devices or liquidsupplementing device need be provided. However, in practice some leakagealong the piston will always occur so that the liquid will have to beaugmented. Since the additional liquid is always more than the leak, acontrol device also will be required to ensure that the differentialpressure across the rolling diaphragm does not vary.

When the pressure level in the working space is controllable, measuresare taken to rapidly adapt the quantity of liquid in the liquid spacebelow the rolling diaphragm to rapid variations of the pressure level.

Another embodiment of the device according to the invention which meetsthe above described requirement comprises a further duct whichcommunicates the first part of the container with its other end andopens into a liquid storage container which communicates, through acontrol mechanism, with the liquid space and in which a pressureprevails that is higher than the pressure in the liquid space below therolling diaphragm. In this manner a certain buffer store of liquid isformed from which liquid can be transported to the liquid space belowthe rolling diaphragm when the pressure level in the working spacevaries.

When in a further embodiment of the device the space on the side of therolling diaphragm remote from the liquid space contains hydrogen gas,the part of the wall permitting diffusion is manufactured frompalladium.

A further embodiment of the device according to the invention comprisesa structure in which the ends of the liquid exhaust duct and liquidsupply duct remote from the liquid space open into a liquid storagecontainer 1n which at least on an average a lower pressure prevails thanin the liquid space below the rolling diaphragm, the opening of the saidliquid supply duct in the storage container being separated from theopening of the liquid exhaust duct in the said container by one or morewire gauzes.

Because the liquid in the storage container is under a lower pressure,the gas dissolved in the liquid will separate in bubble form. Before theliquid is returned to the liquid space, however, it must pass the Wiregauzes, the gas bubbles appearing in the wire gauze and escaping out ofthe liquid along the wire gauze.

Another embodiment of the device according to the invention in which therolling diaphragm engages the liquid with its concave side comprises astructure in which a pressure prevails in the storage container which atleast substantially corresponds to the average pressure which prevailsin the space on the side of the rolling diaphragm remote from the liquidspace, a control valve being provided in the liquid exhaust duct and apumping device being provided in the liquid supply duct. To hold therolling diaphragm taut, a higher pressure will prevail in the liquidspace than in the space on the other side of the rolling diaphragm. Theliquid from that space will be reduced in pressure when it passes thecontrol valve, the diffused gas being released in bubble form. Thesebubbles deposit on the wire gauze and escape out of the liquid. Thedeposited gas can be returned again to the gas space.

In another embodiment of the device according to the invention in whichthe rolling diaphragm engages the liquid with its convex side, apressure prevails in the storage container which is at leastsubstantially equal to the minimum pressure occurring in the space onthe side of the rolling diaphragm remote from the liquid space, acontrol valve being arranged in the liquid exhaust duct and a pumpingdevice being provided in the liquid supply duct.

According to a further embodiment of the device means are provided tobring the liquid in the first part of the container or in the storagecontainer in which the wire gauzes are arranged at a temperature and/orpressure such that the saturation concentration of the gas in questionin the liquid concerned is lower than the saturation concentrationassociated with the temperature and pressure which prevails in theliquid space below the rolling diaphragm. According to a furtherembodiment the device comprises one or more heating elements which canheat the liquid in the first part of the container or in the storagecontainer provided with wire gauzes. As a result of the said heating thesaturation concentration decreases which means that more gas escapes outof the liquid in bubble form so that a cleaner liquid is supplied to theliquid space.

In order that the invention may readily be carried into etfect a fewembodiments thereof will now be described in greater detail, by way ofexample, with reference to the accompanying drawings, in which FIG. 1diagrammatically shows a piston-cylinder combination in which arollingdiaphragm is used as a seal and in which part of the wall of theliquid space below the rolling diaphragm is manufactured from a materialwhich permits diffusion of gas.

FIGS. 2 and 3 show diagrammatically two piston-cylinder combinations inwhich a rolling diaphragm is used as a seal and in which further meansare provided for circulating liquid from the liquid space below therolling diaphragm along a separator consisting of two containersseparated by a wall permitting diffusion of gas.

FIGS. 4 and 5 show diagrammatically two piston-cylinder combinations inwhich a rolling diaphragm is used as a seal and in which further aliquid storage container with wire gauzes is provided for separating andreceiving gas diffused through the rolling diaphragm.

In FIG. 1 reference numeral 1 denotes a cylinder in which a piston 2reciprocates. The piston 2 is connected through a piston rod 3 to adriving mechanism (not shown). The seal between the piston and thecylinder is formed by a rolling diaphragm 4 which with its one side alsobounds a working space 5 and with its other side engages liquidcontained in a space 6. Because the piston .2 and the cylinder 1 havestepped constructions, the space 6 has a constant volume when the piston2 moves in the cylinder. This means that a differential pressure acrossthe rolling diaphragm 4 which is once adjusted is thereby maintained.The rolling diaphragm 4 is manufactured from a flexible substance, forexample a polyurethane rubber. This substance in general permits acertain diffusion of the gas in the working space 5 to the working space6. The gas diffused through the rolling diaphragm will dissolve in theliquid until the saturation concentration is reached. Then the gas willappear as bubbles in the liquid. This has the disadvantage that theliquid becomes more or less compressible so that at a fluctuatingpressure in the working space 5 the rolling diaphragm will showvariations in length.

In order to prevent the occurrence of gas bubbles in the liquid, a part8 of the walls of the space 6 is manufactured from a material whichpermits diffusion of the gas in question. This part of the wall may bemanufactured from the same material as the rolling diaphragm. When theworking space contains hydrogen, the part of the wall may bemanufactured, for example from palladium. The part 8 of the wall forms aboundary with its side remote from the space 6 of a container 10. Thiscontainer cornmunicates, through a duct 12 and a check valve 14 arrangedtherein, with the working space 5. This means that in the container 10at most the minimum pressure can prevail which occurs in the workingspace. When gas has diffused through the rolling diaphragm 4 to theliquid space 6, this diffused gas will diffuse through the part 8 of thewall to the container 10 as a result of the average higher pressure inthe space 6 with respect to the pressure in the container 10. The gasmay then be returned to the working space 5 out of the said container10. In this relatively simple manner it has been achieved that no gasbubbles are formed in the liquid while the dilfused gas is alsorecovered.

FIG. 2 again shows a piston-cylinder combination as shown in FIG. 1. Thecorresponding components have like reference numerals. The walls of theliquid space 6, however, in this case are manufactured from a materialwhich permits no diffusion. 'In this embodiment the liquid space 6communicates with a liquid exhaust duct 15 which, with its other endcommunicates with a part 16 of a container 17. The container 17 isseparated into the parts 16 and 19 by a partition 18 permittingdiffusion. The part 16 again communicates with the liquid space 6through a further duct 20 which includes a pump and a control device 21.

The control device 21 comprises three spaces 22, 23 and 24. The space 22communicates through a narrow duct with the working space 5 so that inthat space the same average pressure prevails as in the working space.The space 23 also communicates through a narrow duct with the liquidspace 6 so that in that space the same average pressure prevails as inthe liquid space 8. The spaces 22 and 23 are separated from one anotherby a diaphragm 25 to which the valve spindle of a valve 26 is connected.In order to maintain a given diiferential pressure between the spaces 5and 6 and 22 and 23 respectively, a pressure spring 27 is provided.

The device further comprises an additional liquid pump 29 which suppliesliquid to the space 6 through a duct 30. As a result of the action ofthe liquid pump in the duct 20 liquid flows out of the space 6 into thepart 16 of the container 17.

Since a pressure is maintained in the space 19 which is lower than theliquid pressure, gas in the space 16 will difiuse through the partition18 which permits dififusion into the space 19. The gas diffused to thespace 19 can be conducted away through duct 31. The space 16 includes aheating element 32 which heats the liquid in that space. As a result ofthe heating of the liquid the saturation concentration of the gas inquestion in the liquid will become lower as a result of which more gaswill diffuse through the partition 18. The liquid flows back to theliquid space 6 out of the space 16 through duct 20. As a result of theseal between the piston 2 and the cylinder 1, some liquid may leak awayunder conditions out of the space 6 into the sump. The liquid pump 29supplies liquid to the space 6 to compensate for the leak losses. Inpractice the pump 29 will supply more liquid than has leaked away. Theexcess liquid has to be conducted away again since otherwise thedillerential pressure across the rolling diaphragm 4 may vary. In orderto ensure a constant differential pressure across the rolling diaphragm4 a control device 21 is provided. When the pressure in the liquid space6 becomes higher than corresponds to the desired differential pressure,the diaphragm 25 will show a deflection upwards, as a result of whichthe valve 26 is lifted and liquid can flow back to the sump out of thespace 24 through the duct 33.

In this manner it is achieved again that the liquid in the space 6remains incompressible in which the gas diffused through the rollingdiaphragm is not lost.

FIG. 3 shows the same piston-cylinder combination as disclosed in FIG.2. The difference is that in this embodiment a storage container 35 isprovided in the duct 20 between the space 16 and the control device 21.On its upper side the said storage container communicates through anarrow duct 46 with the working space 5 so that the average pressure ofthe working space 5 will prevail in the storage container 35. In thestorage container the liquid and the gas are separated from one anotherby a light-weight piston-shaped body 36 which permits no diffusion. Theoperating condition of the said piston-shaped body 36 is determined byan exhaust 37. The storage container contains a comparatively largequantity of liquid which enables the pressure level in the device tovary comparatively rapidly Without the rolling diaphragm 4 beingadversely influenced by it.

FIG. 4 shows a piston-cylinder combination in which the rollingdiaphragm 4 serves as a seal facing the workmg space 5 with its convexside. A liquid exhaust duct 40 which includes a control device 21communicates with the liquid space. The said control device is similarto the control device shown in FIGS. 2 and 3 as faras structure andoperation are concerned, with the understanding that in this embodimentthe spring 27 is constructed as a tension spring as a result of the factthat the rolling diaphragm faces the working space with its convex side.The result of this arrangement is that the average liquid pressure inthe spaces 6 and 23 now is higher by a certain amount than the averagepressure prevailing in the working space. The duct 40 communicates witha liquid container 41 through a control valve. The vapor space of thesaid container communicates through a narrow duct with the working space5 so that in that container the average pressure prevails which prevailsin the working space 5. One or more walls 42 of wire gauze are arrangedin the container 41. The container further comprises a liquid exhaustduct 43 which opens inside the wall of wire gauze 42. The exhaust duct43 includes a pump 44 which brings the liquid to the pressure prevailingin the space 6. Therefore the liquid is circulated by pumping of thepump 44. In this case a reduction in pressure occurs across the valve 26from the average liquid pressure to the average gas pressure. Gas, ifany, dissolved in the liquid will separate. When passing the wire gauzesthe said bubbles are retained on the wire gauzes in the liquid containerand rise upwards. In this manner they again reach the working space. Toobtain a reduction of the saturation concentration a heating element 32is included in the liquid container.

FIG. 5 shows a device which corresponds to the device shown in FIG. 4.However, in this embodiment the rolling diaphragm 4 faces the workingspace 5 with its concave side. To obtain a dilierential pressure acrossthe valve 26 the minimum pressure which occurs in the working space 5prevails in the container 41. This can be achieved by communicating thevapor space with the working space 5 through a duct 50 having a checkvalve 52 and further communicating the vapor space with a supplementcontainer in which the minimum gas pressure prevails. As a result ofthis structure the liquid is reduced in pressure across the valve 26which entails a reduction of the saturation concentration. A furtherreduction of the saturation concentration is obtained by raising theliquid to a higher temperature. In this manner a great quantity of thegas in the liquid is separated with extremely simple means. The liquidwhich is directed back to the liquid space only contains so little gasthat there exists no danger for surpassing the saturation concentrationassociated with the pressure and temperature prevailing in the space 6.

What is claimed is:

1. Apparatus comprising:

a cylinder;

a piston reciprocally movable within the cylinder;

a rolling diaphragm seal secured between the cylinder and piston,thereby separating a first space for containing liquid from a secondspace for containing gas, a quantity of thegas being difi'usible throughthe seal and being soluble in the liquid,

means in communication with said gas and liquid for maintaining apressure differential. across said seal, and

a separator in communication with said liquid and including means forseparating said dissolved gas from the liquid, said separator comprising(a) a container,

(b) a partition through which said gas is diffusible, the partitiondefining in the container a third space for a quantity of said liquidand a fourth space, the dissolved gas being ditfusible through thepartition into the fourth space and thereby removed from the liquid (c)a liquid exhaust duct interconnecting an outlet of said first space andan inlet to said third space;

(d) a liquid supply duct interconnecting an outlet of said third spacewith an .inlet to said first space;

(e) a pump operatively connected to the apparatus for moving the liquidbetween said first and third spaces and,

(f) additional means for maintaining the pressure in said fourth spacelower than in said third space.

2. Apparatus as defined in claim 1 and including a liquid reservoirbelow the piston, wherein said means for maintaining the pressuredilferential across said seal includes a control device comprising:

(a) a chamber,

(b) a diaphragm in said chamber defining a gas space and a liquid space,

(c) a first duct interconnecting said liquid space and said first space(adjacent the seal) for maintaining substantially the same averagepressures therein;

(d) a second duct interconnecting said gas space and said second spacefor maintaining substantially the same average pressures therein (e) athird duct interconnecting said liquid space and said liquid reservoir,

(f) said supply duct comprising a first part interconnecting said thirdspace of the separator and an inlet to said liquid space of the controlmeans and a sec- 7 8 0nd part interconnecting an outlet of 'said liquidlet, a storage chamber outlet arid a control means space and said firstspace, and inlet, and a control means outlet and a first space (g) avalve operatively connected to said diaphragm inlet.

for controlling flow of liquid from said liquid space References Citedinto said third duct whereby excessive pressure in the first space willcause the liquid in the liquid space UNITED STATES PATENTS of thecontrol means to deflect the diaphragm, there- 1,174,631 3/1916 Snenlngby open said valve, and discharge liquid through the 2,635,620 4/ 1953Deal'dol'ff third duct to said reservoir, and relieve the pressure2,824,620 2/1958 De Rosset 55-46 in aid first space PaI'SOnS 3.Apparatus as defined in claim 1 wherein said means 3 3 11/1960 De Rosset5516 for maintaining the pressure difierential across the seal 3,193,9887/ 1965 Kudlaty 92 79 X includes a control device comprising: 3,204,8589/ 1965 f 230-49 a reservoir for the liquid, and 3,277,795 10/1966kletdllk 9284 a liquid storage chamber including therein a piston forseparating liquid below and gas above the piston, the la MARTINSCHWADRON Pnmary Exammer gas being in communication with said secondspace, IRWIN c, COHEN, A i t E i and the liquid in communication withthe reservoir, said supply duct having three parts respectively inter-US. Cl. X.R.

connecting said third space and a storage chamber in- 2 55--16, 158

